Stretch and compression testing device



W. T. CONN STRETCH AND coMPREssIoN TESTING DEVICE FiledDec.

a5 32 /0 26 l5 f June 2, 1936.

frwento: Wallace. Tf Conn /zfto/'ney E Patented `lune 2, 19.367

UNITED vSTATES STRETCH AND COMPRESSION TESTING DEVICE Wallace T. Conn, Lawrence, Mass.,

assignor to Government of the United States, represented by Secretary of Commerce Application December 1, 1932, serial No. 645,282 4 claims. (C1. 265-17) (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 O. G. 757) The invention described herein may be manufactured and used by or for the Government of the United States for governmental purposes without the payment to me of any royalty thereon.

5 My invention relates to a device for determining the intensity of stress, applied to an object, up to and beyond the elastic limit, or yield point, to the ultimate stress point of the same. The use of these terms are intended to mean as defined on page 114 of The Engineers Manual by Hudson, published by John Wiley & Sons, Inc., New York, 1917.

The object of my invention is to provide a measuring device for readily and efficiently measuring compression and tensile strength of materials and particularly for measuring non-rigid materials under a predetermined tension.

For the purpose of a clear understanding of my invention I will describe the same in its use in connection with measuring the stretching ability and length of webbing or mesh of fish nets. It is to be understood, however, that my device is not to be limited to such use only. From the foregoing objects and the detailed description it will be obvious that my device may be used for measuring the elasticity of an object, the intensity of stress applied to an object up to and beyond the elastic limit or yield point, and the ultimate stress point, or for measuring an objects resistance to o stretch or compression.

The accurate measurement of the mesh or Webbing of sh nets and similar non-rigid textiles has been diflicult due to the physical character, the weight and superficial size. For certain control s operations, gauges are used but do not serve as actual and accurate measuring devices. Likewise, inaccuracy has been experienced in springless dead weight measuring instruments due to the non-rigid character of textiles to be measured and, too, measuring instruments having a spring element are inaccurate due to the weakening and stretching of the spring. Furthermore, these devices are seriously affected by vibration and their `use is limited to ideal conditions seldom found in commercial practice and generally prohibitive in factories and particularly on boats where it is frequently necessary to measure sh nets. Among the most common causes of inaccuracy of known instruments are the absence of means for determining the proper tension to be placed upon material, the absence of means for determining the proper rate of speed leading up to a predetermined tension, the absence of means for determining when the reading should be taken and the consequential continual changing in the readings due to continual stretching.

My invention comprises a springless measuring device, relatively light, simple, portable, not seriously affected by vibration, since the controlling 5 weight is not in service except at the moment when a predetermined tension or stress is applied to the material, and can be used in a horizontal plane or vertically. The present invention will be seen to be commercially convenient, eflicient, and 10 accurate. l Y

Other objects will become apparent as the description of my invention is developed with reference to the accompanying illustrative drawing, in which-n 15 Figure 1 is a top plan View of an embodiment of the present invention.

Figure 2 is a view in elevation partly in section and `broken away to show the interior assembly of parts.

Figur' is a cross section showing particularly 20 the mounting of the traveler nut.

Figure 4 is a view of the instrument in bottom plan view.

.Figure 5 is a weighted arm for attachment to 25 the device as shown in Figures l, 2 and 4 when it is desired to use the same in a vertical position.

Referring particularly to character references of the drawing illustrating an embodiment of my invention, I provide a body portion compris- 30 ing a beam or mounting plate 9 having a slot I0 along one side of which a gauge II is provided.

A worm shaft I2 is mounted parallel with the beam or mounting plate by means of a bearing I3 and operated by meansof a thumb screw I4. 35 A nut traveler I5, having a portion thereof extending up through the slot, is mounted on the shaft I2. On the portion of the nut traveler extending up through the slot is provided an indicator I6 cooperating with and reading on the 40 gauge II. 'I'he nut traveler I5 is also provided (Figure v3) with arms I1 adapted to slide in grooves I8. These arms act as supporting means for the nut traveler and shaft and at the same time prevents any rotary movement of the nut. 45 These grooves are formed by stepped strips I9 attached to `the under surface of the beam or plate 9.

A T shaped weight element 2 0 is pivotally mounted-on posts 2li on the member 9 at the end 50 opposite from that of the thumb screw. 'I'his weight element comprises an arm 2l having weight 22, an arm 25 for engaging the material 21 to be measured, and an arm 28 extending down through the member 9 for making and breaking 55 Yso Vas.,y

a'circuit when Vengaging and disengaging the contact point 29 of a battery 30. Additional'sleeve weights may be attached to the weight 22 Vby any desired means such as a screwV 23. Cooperating with the arm 25, for engagingthe material, is Van arin 26 on the portion of the nut traveler Y. I5 extending up through the slot I 0. The battery 30 is carried bythe member S'by means ofi a clamp 3| and is connected to a bulb 32, mountedv TheV bulbv isA'so.

on post 34, by means of wire'33. Y positioned as to throw a beam of light up through the slot as a means for readily indicating a.V predetermined movement of the weight element which is brought about by a proper tension on the material to be tested. Means are provided`fory determining the rate of Ytension or compression, i. e., the: rateof Vspeed with which the material Vis brought up to a denite tension or compression, which Com-'prises a milled or serratedwheel or shoulder on the shaftadgacent to the thumb screw, Vand-cooper'- ating therewith isa resilient dog 36 mounted on.y the beam IlV onpost 31.

vA stop 38V may be provided in order that the initial. pullon. engaging arm 25 is from a point of maximum leverage. When thedevice is used', as hereinafter described, for determining compressiorial ability of objects, this-stop 38v prevents movement of the engaging armv 25A (which may, ifdesi-r'ed for this purposef-besubstituted by ka compression plate) beyond aA position parallel# to Vtheiace fof! the {engaging arm-26 (which mayalso, if desired, be replaced bya `com-pression plate) ontheftraveler nut I5. Y

that! the replacement fof the engaging arms 25 and 26 by pressure platesL adapts Vtheinstrument for use inl measuring thel compressional ability of objects, the method of operation being the re- ;verse adjustment of the thumb screw to provide v shortening of f the space between the engaging arms or plates instead of; lengtheningthe space between the-engaging arms or plates 25 and 26.

When the device is usedina Vertical-position for tension measurement with the thumb Vscrew I41up, the weighted arm 40 shownin Figure 5 is attachedto the pivoted weight element by means of asocket 38am? the-head of the-stop 38. When th'edeviceis used for tensional measurement with 50i-'the thumb screwy I4dcwnthe weighted arm 40 may'belatt'ached by means? of a socket 22a in the weight 2'2", to extendl in the oppositey parallel 'd- Vre'azz'tio'nwfrom fthat just described. .Dependent\ upon which end of the instrument is uppwhen used 5mi-:in a vertical position, the weighted arm 40 should bela-ttached in the plane-of rotation, whereby the Vat-:tionofgravity on the bob 39 of the weighted arm? 4BP-places the material*Y 1271 :runder tension;

tendisftoreston the stop v3B and tends to lengthen YGi'ithe Qsp'aceY between the engaging arms. Preferablythebob39 of the weighted arm 40 isv located adistance Yfrom the axis of" the weight element by Vpositioning 4theweightedarm at'right angles to thearm 2 I'.

-When -the instrument is used in aY vvertical position, with thumb screw I4 at 'the top, for compressicnal measurements, it will be obvious that by screwingvthe weighted arm (Fig. 5) into socket-22a (Fig. 4) the tendency of the weighted Far` 'Y is to move the engaging arm, or plate, 25

intzlicompressional relation arm, orplate,` 26. Or, if the instrument Vis used in Ya-ver-tieal position, with the thumb screwY I4 atv'thef bottom, a similar compressionalI relation iis'attained by screwing arm 40 (Fig. 5') into socket I 0 when the circuit is closed, and operates r It is obvious from the foregoing description` with theV engaging sitions as used for measuring tension, is obviously not necessary if theVL instrument itself is reversed, i. ei, the-reversal of: the instrument itself automatically reverses the effect, from tension to compression, of theV weighted arm. When the instrument is .to beusedfor compressional measure- Y ment ina horizontalplane, although not'shown in the accompanying drawing but obvious to those skilled. inithe. art, the weighted arm 40 should be attached tothe-socket 38a and the weight 22 removed lfrom-its position as shown in the drawi-ng and. attached to socket 40a to extend from a point over the pivot toward the thumb screw I4.

When the instrument is used for compressional measurement the extinguishing of the light indielement brought about by the-proper'pressure on the materialto be: testedi in thesame manner that the Vlightingiof. the bulbi-indicates al predetermined movement of'the weight, brought about by the-.properitensiomlwhenvthedevice is used for tension. measurement.

The obliectfof the `lightisto immediately ind-.icate the-proper tension. or compressionv brought aboutby apredetermined movement of the-weight elementand thereby eliminates the necessity for constantiscrutiny othe-weightelement in order to-.deterniineminute movements thereof.,` However, if desired, the light may be eliminated and any1 means for indicating themovement v of f the weight.. elementf-broug-ht about by pull or compressioni onithe. materialg.. may4 be employed.

.Inl'theioperationsofitheidevice, the materialY to be measunedifissuspended from! engaging arm 25 tot Y engagm'gfanm: 2.2.6. and @the shaftr vI2 A rotated by meansfotrthnmbfsorewrltwherebythe nut travelerIBf, carrying.v engaging. arm'iVZ-, places the material V2li eithezr-under tensionor compression, dependent `upon the: ,desiredv measurement andv position, ofgtherweights... .The nut travelerfriiis moved;untilf-thetqtension sor compressionzfon the suspended'materialgZ-'I ,1 determinedby the weight, is sufiicient .tojlifty the.- weight, against. gravity, to' a predetermined 1 point. point'lbemg indicatedfbyv thexlignting or lextin,guishi-ngy of the bulb Y32,caused/,bythe arm 28 closing or breaking the circuit. 'If'hel proper tension or; compressionV being-once determined, thefreading as indicatedon the gauge Itby the indicator; I can; if. talgen, at anytime regardless ofwhether. the. material thereafter continues, to stretcher compress. Initheoperation, the definite rate of pull or push speed leading up to cates.apredetermined movementV of the weight The predeterminedY a definite tensionor;conncnressionV is a., controlling factor inasmuch as a slow` ratey of pull. or push will permit theL material tor-stretch or,k compress more-beforefreachihg adenite tension or comkpression than. `if the rate ot tension or compression dog 3I from one serration to another or rotations or theY thumb screw I4 ror pointsof movenent'onV tn'jgauge I'I per's'econdgj or other period'of time, mayndicate the rate'of compression of'tension.

It willfbe-understoodf'that the foregoingv descrip'tion Vandl accompanyingl *drawing* compre`` hend only `the generaliand preferred embodiment and uses# of :ny-invention, and-l that minor detail' 5 changes `in the construction and'rarragement Vof 75 parts and uses may be made within the scope of the appended claims Without sacricing any of the advantagesl of my invention.

Having thus described my invention, what I claim is:

1. A springless device for measuring the distortion of an object under a predetermined intensity of stress comprising the combination of a scale, a worm shaft parallel with said scale, a nut traveler mounted on said shaft and cooperating with said scale, means carried by said worm nut for engaging the material to be measured, an L lever pivoted at its angle, one arm thereof carrying a Weight and another carrying material engaging means, an electrical signal, a make-andbreak contact device for operating said signal actuated by said lever, and means to indicate movement of the nut traveler.

2. In a measuring device, the combination of a supporting member, a. plurality of material-engaging elements mounted thereon, one of said engaging elements being pivotally mounted on the supporting member to serve as a make and break contact device, another of said engaging elements being slidably mounted relative to the pivotally mounted engaging element, means to move said slidable element, means toindicate movement of said sliding element, a scale cooperating With said slidable element to measure the movement thereof, and an electrical signaling device operated by the pivotally mounted engaging element, serving as a vmake and break contact device, to indicate a predetermined force applied to the material under test.

3. In a measuring device, the combination of a supporting member, a plurality of material-en'- gaging elements mounted thereon, one of said engaging elements being pivotally mounted on the supporting member, an electrical signal to electrically indicate movement of the pivoted element to a predetermined position, a make and break contact device for operating the electrical signal actuated by said pivoted element, another of said engaging elements being slidably mounted relative to the pivotally mounted engaging element, means to move said slidable element, means to indicate movement of the sliding element, and a scale cooperating with said slidable element to measure the elasticity of said material under a predetermined force.

4. A springless device for measuring the distortion of an object under a. predetermined intensity of stress comprising the combination of a lever arm adapted to engage the material to be tested, means tending to hold the arm in one position, means to exert a force upon the material tending to move the arm in the opposite direction, electrical indicating means, a makeand-break contact device for operating said electrical indicating means cooperating With said lever arm to readily indicate a predetermined force on said lever arm, and means to automatically retain stopping positions of said force exerting means.

WALLACE T. CONN. 

